Who is the unnamed "candidate for federal office" at whose behest Michael Cohen made payments in 2016 to two women with whom President Trump is alleged to have had affairs? It would be very amusing if we were all wrong and it turned out to be Bernie Sanders knifing Hillary Clinton in the back.

This is unlikely. Everyone who has been following the news believes that President Trump is in what legal experts refer to as "deep shit." This has nothing to do with how many Nigerian prince email scams Don Jr. answered or who had a cup of coffee once with somebody with a vaguely Russian-sounding last name or who got the timeline wrong about ordinary meetings with foreign officials. Instead it involves the incontestable violation of federal campaign finance law.

I am not so sure the president will have to answer for it.

There is, simply put, no constitutional framework according to which a sitting president can be prosecuted. Trump is the head of the executive branch. The authority of every federal prosecutor, "special" or otherwise, is derived ultimately from the president, who will not, presumably, submit to some grossly irregular attempt at his deposition. There is, of course, the possibility of a prosecution by one of the states — New York, for example. But what would prevent Trump, if indicted on, say, wire fraud or tax evasion charges in Albany, from haughtily disregarding them? Who in the world has the power — never mind the authority — to compel the commander in chief of the armed forces to appear in court? It's never going to happen.

The only mechanism for punishing Trump is impeachment by the House of Representatives, which is likely to be under Democratic control next year, and removal from office by the Senate, which will remain in Republican hands. The former is, I think, almost certainly going to happen; the latter seems to me supremely unlikely.

Trump has proven over and over again that he is the most popular politician in the country with an R next to his name. He was the only one of the 17 Republican candidates with a chance at winning the election in 2016. He shows every sign of winning again in two years. Mitch McConnell understands this. He will not direct his caucus to vote for impeachment because he understands, I think, that Vice President Mike Pence, running for re-election as a generic lower-taxes Moral Majority Republican, would lose to a halfway competent Democratic challenger in Pennsylvania, Michigan, and possibly Ohio.

Meanwhile the sitting Republicans who affect distaste for the president — Bob Corker and Jeff Flake — are retiring or, in the case of John McCain, unlikely for other reasons to take part in such proceedings. Other occasional critics of Trump, such as Lindsey Graham and Rand Paul, have shown that at the end of the day they are company men. Granting the likelihood of an obligatory squish vote from Susan Collins and a showboating defection from Ben Sasse, even a unified Democratic minority would come nowhere near the two-thirds required to remove Trump.

There also remains the possibility that an indictment could be filed now by Special Counsel Robert Mueller but not taken up until 2021. Is this at all likely? "I shouldn't comment," an unnamed official in the Department of Justice told me when I asked him. But if Trump wins re-election in 2020 he will brush pass the statute of limitations for the offenses in question, which require a prosecution to take place within five years of the date of the alleged crime.

It is easy to imagine a Democratic successor to Trump going after him after 2024 for offenses with a more generous statute of limitations, assuming evidence of such crimes can be discovered. But even if this seemed likely — if it were to become, for example, one of the principal themes of the 2024 Democratic nominee's campaign — I think Trump still gets off the hook. How? At some point in 2024 the president could simply resign, citing his health and insisting that he had succeeded and made America the greatest country in the history of countries and so had nothing left to do. He would be replaced, with a month or two remaining until the election, by the sitting vice president, who could be someone other than Pence if need be — it would be dirty work, after all. This person could issue the sort of blanket pardon that Gerald Ford arranged for Richard Nixon. If Trump is ever prosecuted it will be because he decides to submit to it voluntarily, not because it is forced upon him by his enemies. Otherwise, it seems to me that he is invulnerable.

What are the takeaways from this far-flung but not, I think, baseless speculation? One is that Mueller's special counsel investigation has not been fruitless. It is, after all, thanks to Mueller that Michael Cohen, the president's former attorney, pleaded guilty in New York after admitting that he made payments to two pornographic actresses. But the charges against Cohen, like those on which Paul Manafort was also convicted on Tuesday, have nothing to do with Russian meddling or with collusion between the Kremlin and Trump's campaign. The Mueller investigation is still what its critics have always claimed: an attempt to bring down the duly elected president of the United States by any (legal) means possible.

Which is the real point here. The most significant lesson of the Trump era in American politics is that no one actually cares about so-called "norms" or ethics or hoary phrases like "separation of powers." The same people who feign outrage when the president directs his attorney general to consider investigating the conduct of Obama-era officials would have no problem with Attorney General Kamala Harris prosecuting Trump under any imaginable pretext. The elaborate machinery of our judicial system — prosecutors, indictments, hearings, judges, verdicts — is simply an extension of the ruling party's authority. It cannot be directed against the head of that party, as we were shown during the Clinton administration.